Diagnostic article Generic OBD-II
P212B: When throttle-position information disagrees with the airflow model
Understand the P212B rationality comparison and the source limitations that prevent a guessed sensor replacement.
Read before applying this article
Documented application
2025 GM 25OBDG07A Part 2 monitor tables only; model, engine and transmission applicability are not established by the unresolved application-matrix filename join.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P212B is a rationality diagnosis for throttle-position sensor 2 at bank 2 in this GM source. Its purpose is different from checking whether the raw signal has crossed a voltage limit: it compares independently derived descriptions of throttle opening.
More than one angle estimate is involved
The table describes disagreement between the angles derived from position sensors 1 and 2, together with disagreement between sensor 2 and an angle calculated from the main charge information. A lookup-dependent sensor comparison and an airflow-model comparison are therefore both relevant to interpretation.
An input can remain electrically in range yet be inconsistent with the other evidence. Conversely, the diagnostic's extended logic includes validity and fault information from charge sensing, so disagreement cannot automatically be blamed on the throttle-position sensor.
A limitation in the detailed branch description
The continuation mixes bank 1 and bank 2 references inside this bank 2 diagnostic. This article preserves the supported comparison principle but does not silently resolve those references into a universal numeric test sequence. The exact calibration and service procedure must establish which signals and branches apply.
Useful diagnostic data include both position-derived angles, the charge-derived estimate and the validity of the model's inputs. A simple voltage reading misses those relationships. Before selecting a part, determine which estimate becomes inconsistent and whether an invalid model input explains that inconsistency. The summary does not provide enough evidence to prescribe a throttle body or airflow sensor replacement.
Source and scope
2025 GM 25OBDG07A Part 2 monitor tables only; model, engine and transmission applicability are not established by the unresolved application-matrix filename join. These are documented monitor criteria, not a universal repair procedure. GM PDF, physical page 629 · GM PDF, physical page 630.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Throttle Position Sensor/Switch G Circuit Range/Performance
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT